Lepidochelys olivaceaPacific Ridley; Olive Ridley Sea Turtle

Geographic Range

The Olive Ridley Turtle has a large range within the tropical and subtropical regions in the Pacific and Indian Oceans as well as the Southern Atlantic Ocean. They generally tend to stay within the latitudes of 40° North and 40° South. Around North America it can be found in the waters of the Caribbean Sea and along the Gulf of California. The largest nesting beach for the Olive Ridley Turtle is at the Bhitar Kanika Wildlife Sanctuary on the Bay of Bengal located in Orissa, India.

Habitat

The Olive Ridley Turtle spends most of its time within 15 km of shore, preferring shallow seas for is feeding and sunbathing. However this species is observed in the open ocean as well.

Physical Description

The Olive Ridley Turtle is a large sea turtle that can weigh as much as 45 kg (100 lbs) and have a length of up to 75 cm (30 in). The skin of the turtle is olive gray and the distinguishing feature between male and female turtles is that the male's tail extends past the carapace while the female's does not. The relatively thin shell compared to other turtles is somewhat heart-shaped and is olive in color. Each of the four limbs has two claws.

Reproduction

While the exact age at which reproduction occurs is not known, females usually reach a length of 60 cm before becoming reproductively active. Mating usually occurs on beaches during the spring and early summer in North America and is not monogamous. Male sperm is stored within the female for use throughout the entire breeding season. Mating takes place just offshore of the breeding beaches. Females choose to return to their beach of birth and will do this by remembering the smell of the beach through enhanced chemosensors. Nesting takes place during the night with the females riding in on the high tide and usually coincides with the first or last quarter of the moon. The Olive Ridley turtle is well known for its mass nesting, with 300 or more females at a time coming ashore. Situating themselves approximately 50 m from the sea, females will dig a nest 30-55 cm deep, depositing on average 107 eggs, and then return to the sea. This entire process takes the female turtles less then an hour. Since females store sperm in their bodies for later use, a single female can nest multiple months in a row. The eggs resemble white ping-pong balls and hatch within 45-51 days depending on incubation temperatures, which will also determine the sex of the turtle. The turtles face varying degrees of success in each of the clutches that are laid in large groups to increase their success of surviving.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)

Behavior

Not much is known about the behavior of this turtle besides that it makes regular migrations to and from the nesting beaches during each year. During a typical day the turtle will feed during the morning hours and sun bathe at the surface of the ocean during the afternoon. Large groups of turtles have been observed basking together in the afternoons so as to escape the cold water temperatures below them and maintain a warm internal temperature by help of the sun. In the warmer areas where the waters are shallow and warm, the Olive Ridley Turtle is usually not observed spending time sun bathing. The Olive Ridley Turtle will normally swim away or dive to deeper water rather than confront a predator, which often are humans. On land, opossums, wild pigs, and snakes prey upon the eggs. Mature females will defend themselves while on land by flapping their front forelimbs.

Food Habits

The Olive Ridley is a chiefly carnivorous species feeding on invertebrates and protochordates such as jellyfish, snails, shrimp and crabs. The Olive Ridley Turtle has a tendency to eat a wide variety of foods which has lead to many attempts on its behalf to ingest trash such as plastic bags and Styrofoam. Surprisingly, in captivity, this species has been observed to be cannibalistic. Most feeding takes place in shallow, soft-bottomed waters. The Olive Ridley Turtle has also been known to principally feed on algae in areas devoid of other food sources.

Economic Importance for Humans: Positive

Since turtle egg harvesting became legal on the Playa Ostional in Costa Rica in 1987, local villagers have been able to sell nearly 3 million eggs collected from the beaches each season. The villagers can legally harvest only eggs laid during the first 36 hours of a nesting period since any turtles nesting after this period would destroy them. Approximately 27 million eggs are left unharvested and are protected from predators such as snakes and birds by the villagers.

Economic Importance for Humans: Negative

As with other large sea turtles, the Olive Ridley Sea Turtle is considered somewhat of a pest for commercial fishermen for they often find these turtles caught in their nets.

Conservation Status

Within the past thirty years the Olive Ridley Turtle has experienced population loss due to hunting at nesting sites for the female's skin and meat. The Olive Ridley Turtle is still the most abundant of all sea turtles, yet it nests at only five beaches in the world. Governments are in the process of protecting these nesting sites and populations. The United States has passed a law requiring that all shrimp sold in the United States must be harvested by companies with "Turtle Excluder Devices" that allow sea turtles to safely escape capture in shrimping nets.

Contributors

Peter Herbst (author), University of Michigan-Ann Arbor.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

References

Anonymous. 11/7/97. Marine turtles in Australia http://www.anca.gov.au/plants/manageme/rid.htm. Environment Australia ~ Biodiversity Group.

Anonymous. 11/7/97. Olive Ridley Sea Turtle (Lepodochelys olivacea). http://www.c-c-i.com/saveturtle/olive_ridley.html.

Anonymous. 11/7/97. Biology http://www.puertovallarta.com/Corpamb/biology.html.

Anonymous. 1997. Save India's Bhitar Kanika: Critical olive ridley sea turtle nesting beach. http://www.earthisland.org/ei/strp/india.html. Sea Turtle Restoration Project.

Bruemmer, Fred. La Arribada. Natural History 104: p. 36-43.

Burton, Lisa. 1995. The Olive Ridley Turtles of Ostional. http://odin.community.net/marsh/news2.htm. Suisun Marsh Natural History Association.

Ernst, Carl H. and Roger W. Barbour. 1994. Turtles of the United States and Canada. Smithsonian Institution Press. Washington and London. p 83-88

Mer, Jeffery. Turtle Project Can't Outrun Bureaucracy. Science 276: p. 1785.

Plotkin, T., R. A. Byles, D. C. Rostal, D. W. Owens. 1995. Independent versus socially facilitated oceanic migrations of the olive ridley, Lepidochelys olivacea. Marine Biology 122: p137-143.

Pritchard, Peter C. H. and Pamela T. Plotkin. 1/15/97 Olive Ridley Sea Turtles http://kingfish.ssp.nmfs.gov/tmcintyr/turtles/oliverid.html.

Singh, Rahul. 5/7/97. The Olive Ridley Turtle becomes an endangered species in India.

http://www.earthtimes.org/may/indiatheoliveridleymay7_97.htm. The Earth Times News Services.